In this video, we're going to begin our lesson on the conjugation of HFR cells, as well as the conjugation of f prime cells. However, in this video, we're only going to focus on the conjugation of HFR cells. And then later in a different video, we'll focus on the conjugation of f prime cells. And so in order to understand HFR cell conjugation, it's first important to highlight an important fact. And that is that f plasmids have the reversible ability to integrate itself into the host chromosome, and it can also excise or remove itself from the host chromosome.
An HFR cell, where the HFR really stands for high frequency of recombination, these HFR or high frequency of recombination cells are simply cells that have an f plasmid integrated into the host chromosome. And so if we take a look at our image down below, specifically on the left-hand side over here, notice that this box is focused on the reversible HFR cell formation. And so notice that the top cell that you see here is actually the same F plus cell that we talked about in our previous lesson videos because it's a cell that contains the entire F plasmid and therefore it forms this pilus that you see over here. Now again, this f plasmid has the ability, reversible ability, to integrate itself into the chromosome. And so that means that this plasmid has the ability to integrate here into the DNA of the host.
And so when it does integrate, represented by this blue arrow down below, that is what forms the HFR cell. And so the HFR cell is a cell that has an integrated f plasmid into the chromosome as you see here in this image. Now again, the integration of this f plasmid is reversible, which means that the F plasmid can excise itself or remove itself to become the F plasmid again. And so that's what we see here with the excises arrow pointing back upwards, shows you that the F plasmid once again can come back out, and become an F plus cell. And so, what we can see here is that F plus cells and HFR cells can be converted into each other depending on the integration status of the F plasmid.
If the F plasmid is integrated, it's an HFR cell, whereas if the F plasmid is not integrated, it's an F plus cell. Now in our last lesson video, we were able to talk about the conjugation of these F plus cells. And so in this video, we're going to be focusing on the conjugation of these HFR cells. And so during the conjugation of the HFR cells, these HFR cells are going to serve as the donor cells and the transfer of chromosomal DNA to the recipient cell via conjugation. And so instead of only transferring the F plasmid, in an HFR cell conjugation, part of the donor cell's chromosomal DNA is going to be transferred, and that is a big difference from what we saw in our previous videos.
Now what we'll see is that there are also some similarities between the conjugation of HFR cells' chromosomal DNA and the conjugation of the F plasmid and E. Coli. There are some similarities between the two. However, there are also some key differences. And so, some of those key differences include the fact that HFR cells, they are going to be making the f pilus to conjugate with the f minus cell. However, the entire integrated f plasmid is not going to be transferred to the recipient, which means that at the end of conjugation the recipient is still going to remain f minus and so the recipient stays f minus from the beginning to the end of the conjugation process. And so this is very different than what we've seen in our previous videos where both cells were, F plus at the end of conjugation. However, here with HFR cell conjugation, the recipient stays f minus. And this is again because the recipient does not receive the entire f plasmid. Now, again, we can emphasize that only a really, really small portion, only small portions of the donor cell's, chromosomal DNA as well as a small portion of the f plasmid are going to be transferred to the recipient.
And so, that transferred DNA that the f minus recipient cell receives is either going to integrate into the recipient cell's host chromosome or it will be degraded and have no effect. And so if we take a look at our image down below, we can get a better understanding of HFR cell conjugation. Now over here
